The present invention relates to a plastic package for accommodating a semiconductor integrated circuit device, more particularly to a method of packaging a power semiconductor device using a lead frame and a plastic package produced by the packaging method.
In many of power semiconductor device packages produced by several conventional packaging methods, a power semiconductor chip having low power consumption of 0.5 Watt or less is packaged in a plastic base, and another power semiconductor chip having relatively high power consumption of 0.5 Wait or more is packaged using a ceramic base, a metal frame, and the like, so as to dissipate heat created while operating.
Such a plastic package in which a power semiconductor device is packaged has some disadvantages that the interface between the semiconductor device and a sealing material is peeled off and that the device is frequently cracked by the difference in thermal expansion coefficient between the semiconductor chip and the sealing material. Furthermore, in this plastic package, there arises a drawback that the power semiconductor chip is deteriorated in its high frequency characteristics because of the above-described disadvantages.
In order to improve high frequency characteristics of a power semiconductor chip in a ceramic package, it is required to deposit metal as castellation of a ceramic member and to use a metal lid electrically connected to a ground metal via, so that noise generated in the package may be shielded by metal castellation and ground via. Thus, the processes for packaging a power semiconductor device are complicated and result in high cost required for packaging.
Furthermore, this conventional ceramic package has a resonance of a high frequency signal, so that high frequency characteristics, such as power gain and noise figure value are deteriorated.
In order to remove resonance of a high frequency signal generated in the conventional ceramic package, a metal frame type package has been recently developed. Such a metal frame type package has an improved high frequency characteristics, but has a drawback of difficulty in packaging.
Also, since characteristics of a power semiconductor device is significantly dependent upon a power gain and a noise factor, a multi-layer ceramic type package has been positively studied in consideration of an impedance matching so as to improve a high frequency characteristics of a power semiconductor device therein.